I'm not certain that the chatterbox ought to be logged.
Of course someone can always log it for her or himself,
but that doesn't mean it should be an included feature.
It seems to me that a lot of what happens on chatterbox
is unimportant or only important at the time.

Logged chattering could lose context. Context is not
just a factor of date/time, which can easily be logged
(although which time zone would be used?), but also can
relate to activity on the site (recent postings, who
is logged in at the time) or events outside of the site.

For example, if someone made a post and failed to use
code tags, I might mention that on chatterbox (without
using msg if that person were the only person logged
on). The person doesn't reply but fixes the post.
This is a boring example. Who cares about some missing
code tags?

Next the person writes something insulting me for even
bringing the code tags up (or a poem talking about how
wonderful I am for mentioning it, depending on what view
of human nature you prefer in examples). I'm tired, so
I say more than I might have otherwise--"You are
so rude. I wish someone would rm you." (alternate:
"Please remove that, it's embarassing!").
Point having been made, the person changes the text of
the node so that it says "Oops, sorry for the blank
message, please remove this." Three hours later, it
gets removed. Seven hours later someone looks at the
log and wonders what I'm on and whom I was talking to.

I know, these are silly examples because nobody really
cares what I was saying to the unknown person at 2 in
the morning. Which is exactly my point: if it's important,
it belongs in a node; if it's in the chatterbox, it's
probably disposable (and if it isn't, someone should write
it up in a node so it will be saved).